This invention relates in general to vehicle brake assemblies and in particular to a mounting stud retention system for use in such a vehicle drum-in-hat disc brake assembly.
Most vehicles are equipped with a brake system for slowing or stopping movement of the vehicle in a controlled manner. A typical brake system for an automobile or light truck includes a disc brake assembly for each of the front wheels and either a drum brake assembly or a disc brake assembly for each of the rear wheels. In some instances, the disc brake assembly can be a xe2x80x9cdrum-in-hatxe2x80x9d type of disc brake assembly. The brake assemblies are actuated by hydraulic or pneumatic pressure generated when an operator of the vehicle depresses a brake pedal. The structures of these drum brake assemblies and disc brake assemblies, as well as the actuators therefor, are well known in the art.
A typical drum-in-hat type of disc brake assembly includes a hydraulically or pneumatically actuated disc service brake and a mechanically actuated drum-in-hat parking and emergency brake. The disc service brake includes a rotor which is secured to the wheel of the vehicle for rotation therewith. The rotor includes a pair of opposed friction plates which are selectively engaged by portions of a caliper assembly. The interior of the rotor defines a cylindrical braking surface.
A caliper assembly is slidably supported by pins secured to a mounting flange. The mounting flange is secured to a non-rotatable component of the vehicle, such as the steering knuckle or the axle flange. To accomplish this, typically two threaded bolts extend through the mounting flange and are received in threaded apertures provided in the non-rotatable vehicle component to thereby secure the mounting flange to the non-rotatable vehicle component. The caliper assembly includes a pair of brake shoes which are disposed on opposite sides of the rotor. The brake shoes are operatively connected to one or more hydraulically actuated pistons for movement between a non-braking position, wherein they are spaced apart from the opposed friction plates of the rotor, and a braking position, wherein they are moved into frictional engagement with the opposed friction plates of the rotor. When the operator of the vehicle depresses the brake pedal, the piston urges the brake shoes from the non-braking position to the braking position so as to frictionally engage the friction plates of the rotor and thereby slow or stop the rotation of the associated wheel of the vehicle.
The drum-in-hat parking and emergency brake includes a pair of opposed arcuate brake shoes which are supported on a backing plate for selective movement relative thereto. The backing plate is secured to the mounting flange, or alternatively, can be formed integral therewith. To accomplish this in the case of the former type of structure, typically four threaded bolts extend through openings provided in the backing plate and through openings provided in the mounting flange and nuts installed thereon to secure the backing plate to the mounting flange. In order to retain the bolts in place during shipment, there are two known methods that are commonly used. In one method, the bolts have serrations provided along a portion thereof which frictionally engage the surface of the opening provided in the mounting flange. In the other method, the openings of the backing plate are generally D-shaped and threadably engage a portion of the thread of the bolt.
Each of the brake shoes of the drum-in-hat parking and emergency brake has a friction pad or lining secured thereto. The brake shoes extend within the cylindrical braking surface of the rotor. To effect parking and emergency braking action, the operator of the vehicle manually pulls an actuating lever. The lever is connected to an actuation cable having a park brake cable end which, when pulled, actuates a mechanical actuating mechanism. The actuating mechanism is located adjacent one of the ends of the brake shoes and is operative to move the brake shoes outwardly apart from one another such that the friction pads frictionally engage the cylindrical braking surface of the rotor. Such frictional engagement causes slowing or stopping of the rotational movement of the rotor and, therefore, the wheel of the vehicle in a controlled manner.
This invention relates to a mounting stud retention system for use in a vehicle drum-in-hat disc brake assembly. The brake assembly includes a backing plate and a drum-in-hat adapter. The backing plate is adapted to support a drum brake shoe assembly of a drum-in-hat parking and emergency brake portion of the drum-in-hat disc brake assembly. The drum-in-hat adapter is adapted to support a disc service brake portion of the drum-in-hat disc brake assembly. The backing plate has a centrally located aperture and a plurality of first openings formed therein about the centrally located aperture-thereof and a plurality of second openings formed therein. Each of the first openings has at least one raised tab provided thereon adjacent the opening. The drum-in-hat adapter has a centrally located aperture and a plurality of openings adapted to be aligned with the first openings of the backing plate. The brake assembly includes a fastener extending through each of the second openings of the backing plate and into the drum-in-hat adapter to thereby secure the backing plate to the drum-in-hat adapter. The brake assembly further includes a mounting stud disposed in and extending through each of the first openings of the backing plate and the openings of said drum-in-hat adapter to thereby secure the drum-in-hat adapter to an associated component of the vehicle. In accordance with the present invention, the raised tab of the backing plate is operative to capture and retain the mounting stud in the openings of the backing plate and the drum-in-hat adapter prior to assembly of the vehicle drum-in-hat disc brake assembly to the vehicle.